Process and utility systems integration and optimisation for ultra-low energy milk powder production

Abstract

This study applies a Total Site Heat Integration approach in conjunction with a detailed process and utility model, to develop an innovative ultra-low energy milk powder plant design. The basis for the analysis is a state-of-the-art modern milk powder plant that requires 5,265 MJ/t p of fuel and 210.5 kWh/t p (58.5 MJ e /t p ) of electricity. The model of the modern milk powder plant was validated against industrial data and changes to process and/or utility systems are targeted and implemented into the model to understand the impacts on thermal and electrical demands and emissions. Results show that seven significant changes are beneficial: (1) pre-concentration of milk to 30 % using reverse osmosis, (2) a two-stage intermediate concentrate (30 %) homogenisation to enable high solids (60 %) spray drying, (3) an ultra-low energy Mechanical Vapour Recompression

A comparative assessment of electrification strategies for industrial sites: Case of milk powder production

“…The specific energy use for scenario 3 was found to be 0.86 MWh per ton milk powder and 1.06 MWh per ton milk powder for scenario 4. These values are slightly higher than the thermal energy use of 0.59 MWh and electric energy use of 0.15 MWh per ton of milk found for the best configuration only considering the production in [15]. The best configuration was more advanced and also considered improvements to the spray dryer, reverse osmosis for pre-concentration and direct steam injection for pasteurization.…”

“…A factory to produce milk powder with an ultra-low energy input was studied by Walmsley et al [15]. Their approach applied a total site analysis, the implementation of evaporators with mechanical vapour recompression (MVR) and excess heat recovery of the drying air.…”

“…While many studies address strategies to lower fuel related CO2-emissions in industries, the accomplishment of this goal through electrification is not sufficiently studied. Research has focused on energy efficiency and fuel substitution at industrial sites [9,15,16] or on system studies [3,5,6] for the electrification of a country, but little work has been performed on implementing an optimised all-electric production site.…”

Increasing energy efficiency of milk product batch sterilisation

“…At the process level, previous works in the area of dairy processing include a comprehensive analysis of milk powder production [14] as well as key processes such as the evaporation system [15] and spray dryer [16]. More recent, Walmsley et al [17] integrated the utility and process systems to further raise the level of energy efficiency.…”

“…Curing processes around 100 °C with longer holding-times are called sterilisation processes [27]. Compared to the presented examples on milk powder production [17] and pasteurisation [18], the described sterilisation batch process treats fluid product streams and uses jacketed heat exchangers in tanks. In discontinuous processes such as this batch sterilisation process, the heating and cooling requirements significantly change over time.…”